[New concepts related to implantation. III. Biochemical characteristics].

The fixed position of trophoblast in the uterus is preceded by zygote orientation and its contact, adhession and fusion with endometrial cell membrane. These interactions take place in a precise site called "implantation site". The identification of this area by the administration of pontamine blue has allowed biochemical studies which showed an increase (in the site) of glycolytic enzymes activity of the pentose cycle, of beta-glucuramidase and of acid and alkaline phosphatase; with a decrease in catepsine D activity. In non implanted tissue, isocitric dehydrogenase activity is decreased. From the biochemical standpoint the implanted endometrium may be different from the rest, which allows a better knowledge of possible molecular mechanisms related with implantation, as well as the possible inhibition with medication.